1. Field of the Invention
The present invention relates to a photosensitive body and an electrophotographic printer using the photosensitive body.
2. Description of the Related Art
Conventionally, an electrophotographic printer uses a photosensitive body which is has a drum or tube shape or an endless belt mounted on rollers. The drum or tube type photosensitive body has a photosensitive surface on its outer circumference. The belt type photosensitive body has a photosensitive surface on one of its sides.
In the conventional electrophotographic apparatus, a printing operation is carried out as follows. Firstly, all the charges remaining on a photosensitive surface from a preceding printing are erased by being exposed to an erase lamp. Next, an electric charge is uniformly applied to the photosensitive surface by a corona or a charge roll. After this, a laser beam or LED light is applied to the photosensitive surface so as to form an electric charge distribution corresponding to an image to be printed. Toner is attracted to this photosensitive surface corresponding to this charge distribution, forming a toner image. This toner image is transferred directly or through an intermediate medium onto a recording medium such as a paper sheet and a film.
In this electrophotographic printer, after repetition of image forming, the photosensitive body is deteriorated electrically or thermally. Accordingly, the photosensitive body need to be replaced periodically. The photosensitive body is an important component which directly affects an image formation process. Consequently, when storing or replacing a photosensitive body, countermeasures should be take against possible damages due to dust and deterioration due to sunlight or room illumination.
To cope with this, the photosensitive surface is covered with a protection film, which is peeled off after the photosensitive body is mounted on a printer apparatus. However, peeling off of this protection film is a troublesome work if it should be carried out manually with care not to expose the photosensitive body to an external light.
Japanese Patent, Publication of Examined Application, B2-3-44299 discloses an invention for automatic removal of this protection film. That is, the protection film is wound up by a roller and discharged out of a printer apparatus.
However, the aforementioned invention only peels off and discharges the protection film from the printer apparatus as its purpose. If any trouble has occurred during the peeling-off or discharge operation inside the printer apparatus, an operator cannot know the state inside.
Moreover, it is difficult to check the deterioration degree of the photosensitive body provided inside the electrophotographic printer and there has been a problems that a printed image is deteriorated without knowing.